Motorcycle speedometer drive



P 1943. w. L. CARLSON MOTORCYCLE SPEEDOMETER DRIVE Filed Feb. 21, 1942 2Sheets-Sheet l 3m entor 90712217 4. (a i/sozz G ttornegs Sept. 14, 1943;w. L. CARLSON MOTORCYCLE SPEEDOMETER DRIVE Filed Feb. 21, 1942 2Sheets-Sheet 2 -7lllflllll r oillllllllliilllll 3nventor .Qlz fuk 0C.(kz/sozz Patented Sept. 14, 1943 MOTORCYCLE SPEEDOMETER DRIVE Wilbur L.Carlson, Rochester, N. General Motors Corporation, corporation ofDelaware Y., asslgnor to Detroit, Mich, a

Application February 21, 1942, Serial No. 431,810

7 Claims.

The present invention relates generally to speedometer driving mechanismand more particularly to the location and construction thereofespecially for use on motorcycles. It is an object of the invention toprovide a speedometer driving mechanism in which there is a direct driveto the speedometer from the front axle and thereby eliminate flexibleshaft or angular connections which are used in present types ofmotorcycle speedometer drives.

A further object is the provision of a speedometer driving mechanismwhich is fully enclosed and protected within a portion of the resilientsuspension for the front axle.

A still further object is to provide a speedometer driving mechanismwherein telescoping shaft sections are mounted within telescoping partsof a front axle suspension incorporating a hydraulic shock absorber.

Other objects and the advantages of the present invention will beapparent from the following description of the embodiment thereof whichis illustrated in the accompany drawings in which:

Figure 1 is a fragmentary side elevation of the front portion of amotorcycle with parts in vertical section to show the front axlesuspension and speedometer driving mechanism.

Figure 2 is an enlarged, fragmentary vertical section of parts of. thefront axle suspension and speedometer driving mechanism shown in Figure1.

Figure 3 is a fragmentary transverse view with parts in section takensubstantially on line 3-3 of Figure 1.

Figures 4, and 6 are sections taken respectively on lines 4-4 and 5-5 ofFigure 3 and line B-6 of Figure 1.

Referring first to Figure 1, the motorcycle frame which is indicated at2 is provided with the head 4 adjacent its front end for the usualswivel mounting of the steering fork which includes the steering head 6and the spaced depending fork arms indicated generally at 8 betweenwhich is 'ournaled the front wheel I.

The steering head 6 is provided with the usual handle bars such as shownin part at l2, and is adapted to mount the usual controls andinstruments of which only the headlight I4 and speedometer [6 have beenillustrated. As will be apparent from the showing in Figure 1, thespeedometer I6 is located within the steering head with the axis of itsdrive shaft in substantial alinement with the longitudinal axis of oneof the fork arms 8 to provide for a direct drive to the speedometer aswill be fully described hereinafter.

The front axle is mounted for movement relative to the motorcycle frameby telescoping parts with a spring suspension and hydraulic shockabsorber or clamping means incorporated in the construction of the twofork arms 8 which are identical insofar as details of these features areconcerned.

Each of the fork arms 8 includes inner and I outer spaced concentricsleeves l8 and 20 which are secured at their upper ends to the head 6and a sleeve 22 secured at its lower end to a bracket 24 to which theaxle housing 26 is detachably secured as by bolts 28. The sleeve 22extends upwardly between the sleeves I8 and 20 and is provided with abearing member 30 adapted to engage and slide on the inner sleeve l8.The spring suspension for the front axle is pro vided by a coil spring32 which is secured at its lower end to the bracket 24 and at its upperend to a bracket 34 on the lower end of the outer sleeve 28. The spring32 and outer sleeve 20 are protected and enclosed by relatively thinmetal telescoping sleeves 36 and 38 connected as shown to the head 6 andbracket 24, respectively.

Referring now to the hydraulic shock absorber or damping means, thelower end of the inner sleeve l8 carries a valve 40 which is interposedbetween this sleeve and sleeve 22 and is mounted for limitedlongitudinal movement on sleeve I8 between a shoulder 42 and a screwmember 44. The valve 40 is formed at its lower end with a tapered valveseat adapted to engage a tapered seat on the screw member 44 when in itslowermost position and the inner surface of valve 40 is formed withlongitudinal grooves or flutes 46 to provide passages through or pastthe valve when the valve seats are not in engagement. An annular chamber48 is thereby provided between the sleeves l8 and 22 which extends fromthe bearing member 30 to the valve 40 and the sleeve [8 is provided withrelatively restricted openings 50 into this chamber.

Any suitable fluid such as lubricating oil is placed within the lowerportions of sleeves I 8 and 22 and the construction described abovefunctions as a damping means in the following manner. As the axle andsleeve 22 move upwardly the valve 40 will rise and as the chamber 48expands in length by movement of bearing member 30 away from the valve40, fluid will be drawn into the chamber 48 past the valve. The upwardmovement of the axle and sleeve 22 will be resisted by the compressionof coil spring 32 ball bearings 64.

and when the-axle and sleeve 22 move downwardly, the valve 80 will seaton screw member 44 and the fluid which is then being compressed betweenbearing member 10 and valve 40 can escape only slowly through therelatively restricted openings 50 in sleeve 18. Thus it will be apparentthat this arrangement provides a damping means or hydraulic shockabsorber for the downward movement or rebound of the axle.

The upper end of sleeve 22 is provided with a suitable sealing means 52which engages the sleeve l8 and openings 54 are provided in the sleevel8 adjacent the sealing means to permit the return to within the sleeveI8 of any fluid which may escape from chamber 48 between the sleeve I8and bearing member 30. Openings 56 may also be provided in sleeve 18above the sealing means 52 to limit the amount of fluid that may becontained within sleeve l8 and provide a safety overflow for any excessfluid The front wheel I is secured as shown in Figure 3 to the axle 58by means such as the brake drum 60 and the axle 58 is journaled in thespaced axle housings 26 by needle bearings 62 and As previouslymentioned, the axle housings 26 are detachably secured as by bolts 28 tothe brackets 24 at the lower ends of the fork arms 8 and it willtherefore be apparent that the entire wheel and axle assembly may bereadily removed and installed as a unit.

Proceeding now to the description of the speedometer driving mechanismwhich is adapted to be primarily associated with and contained withinone of the fork arms 8, it will be seen that the axle 58 is formedadjacent one end with suitable gear teeth 66 adapted to mesh with a wormgear 68 on shaft mounted within one of the axle housings 26 by a bearingsleeve 12 and a removable end cap 14. The enlarged upper end of the gearshaft 10 is formed with a bore '00 receive the end of a drive shaft 16and a slot 18 to receivea driving key 80 on the end of shaft 16 tothereby provide a disconnectible drive joint between the parts of thespeedometer driving mechanism mounted within the fork 8 and head 6 andthe parts mounted in the axle housing 26.

The lower portion of the drive shaft 16 extends through a tube 82 whichis secured at its lower end to the bracket 24, and a spring 84 aroundthe shaft 16 within the tube 82 is interposed between an abutment 86fixed within the tube and a shoulder 88 on shaft 16 to force the shaftdownwardly and hold the driving key 80 within the slot 180i the gearshaft 10. The upper end of the tube 82 is provided with a bearing member90 for the drive shaft 16 and downward movement of the shaft is limitedby engagement of a stop 92 on the shaft with the bearing member 80. Thetube 82 is provided with an opening 94 adjacent its upper end to admitthe shock absorber fluid such as lubricating oil which may be containedwithin the sleeves l8 and 22 as heretofore described.

The upper end of the drive shaft 16 is squared as indicated at 86 andadapted to slide within a driving sleeve 98 which is secured at itsupper end to the speedometer shaft and formed at its lower end with asquared portion Inn to engage the squared portion of the drive shaft 16.A hearing member N12 for the driving sleeve 98 may be secured within,the sleeve [8 adjacent the squared portion I00. The speedometer l6 maybe of any standard construction and has been shown,

as including the usual indicating pointer I and a scale I86 which arevisible through a lens I08 mounted within an opening in the steeringhead 6. Although shown and described in connection with a motorcyclefront axle, it will be understood that the present speedometer drivingmechanism may be not only employed in motor tricycle construction butmay also be used with other types of wheel suspension than thatdisclosed herein. It will also be understood that I contemplate all suchchanges and modifications in the specific construction shown herein asmay come within the scope of the appended claims.

I claim:

1. In a motorcycle, a frame, a wheel axle, a steering head swiveled onsaid frame, a front wheel fork including spaced hollow fork armsextending downwardly from said head, means for mounting said wheel axleon the lower ends of said fork arms, a speedometer mounted on said head,and means connecting said axle to said speedometer including a driveshaft extending longitudinally within one of said hollow fork arms.

2. In a motorcycle, a steering head, a front wheel fork including spacedfork arms extending downwardly from said head, each of said fork armsincluding telescoping members, a wheel axle mounted in the lower ends ofsaid fork arms, a speedometer mounted on said head, and means connectingsaid axle to said speedometer including telescoping shaft sectionsextending through one of said fork arms.

3. In a motorcycle, a wheel axle, a steering head, a front wheel forkincluding spaced fork arms extending downwardly from said head, each ofsaid fork arms including a pair of telescoping sleeves connectedrespectively to said head and axle, a spring interposed between thesleeves of each fork arm, a speedometer mounted on said head, and meansconnecting said axle to said speedometer including telescoping shaftsections extending coaxially within the sleeves and spring of one ofsaid fork arms.

4. In a motorcycle, a wheel axle, a steering head, a wheel forkincluding spaced fork arms extending downwardly from said head, each ofsaid fork arms including a pair of telescoping sleeves connectedrespectively to said head and axle and means associated therewith toprovide a spring suspension and hydraulic damping I means for said axle,a speedometer mounted on said head, and means connecting said axile tosaid speedometer including telescoping drive shaft sections extendinglongitudinally within one of said fork arms.

5. In a motorcycle, 9. wheel axle, a steering head, a wheel forkincluding spaced hollow fork arms extending downwardly from said head,spaced axle housings for said wheel axle, means to detachably securesaid housings to the lower ends of said fork arms, a speedometer mountedon said head, and means connecting said axle to said speedometerincluding a drive gear and gear shaft mounted in one of said axlehousings, a drive shaft having one end connected to said speedometer,said drive shaft being mounted within one of said hollow fork arms, anda disoonnectible drive connection between the other end of said driveshaft and said gear shaft.

6. The elements set forth in claim 5 in which said disconnectible driveconnection comprises a key and slot iolnt'between the adjacent ends ofsaid drive shaft and gear shaft, and resilient means to normally preventthe endwise separation thereof.

7. In a motorcycle, a steering head, a wheel said speedometer from said.axle including a drive gear and gear shaft mounted in one of said axlehousings, telescoping shaft sections mounted in one of said fork arms,means to connect one of said shaft sections to said speedometer, and adisconnectible drive joint between the other of said shaft sections andsaid gear shaft.

WILBUR L. CARLSON.

